The present invention relates to a method of assembling from a network of deltatrihedrals a multifaceted corner polyhedra reflector and, more specifically, to a network and method of constructing polydeltatrihedral corner reflector having three mutually perpendicular intersecting planes.
It is a well known phenomenon that a triplanar corner formed by the intersection of three mutually perpendicular planes will focus and redirect radar energy directly back toward the source. The term "corner reflector" as known in the art is typically utilized for marking obstructions, serving as navigation points and for radar purposes. In its most typical configuration, a radar reflector polyhedron, referred to as an octahedron, is formed from eight such corners and provides eight maximum reflecting lobes within a circumscribed sphere, each lobe consisting of a 40.degree. cone. The present invention provides a novel system for assembling any number of similar configurations, some of which have never been considered, until now, for use in the manner herein prescribed.
A theoretically perfect omnidirectional radar reflector reflects incident waves uniformly in all directions and takes the form of a sphere. However, the convex reflective surface which a sphere presents to incident waves for the most part reduces the percentage of transmitted energy which is reflected back to a receiver. It has been determined that the theoretical optimum retrodirective response of a reflector is produced by a perfectly conductive planar member in which the incident radar energy is transmitted toward the plane normal thereto. However, such a reflector is considered to be extremely directional, and even a slight departure from the normal axes produces a substantial reduction in the usable reflected energy.
An omindirectional radar corner reflector, for example, has been developed wherein an array of twenty trihedral corners, i.e., three planes each mutually perpendicular, are distributed on the surface of a sphere as described in U.S. Pat. No. 3,039,093. The solid formed by this configuration is referred to as an icosahedron corner reflector, being a variation of the regular polyhedron referred to as an icosahedron, wherein each of the trihedrals consists of mutually perpendicular planes having an open frontal face projection of an equilateral triangle. The icosahedral corner reflector described by the instant patent is constructed of a plurality of triangular corner reflectors disposed in an edge-to-edge relationship such that the outer edges thereof from a portion of the resulting icosahedron conforming to a quasi-spherical shape. Twenty right trihedrals are assembled in edge-to-edge relationship with their apexes directed inwardly toward a common center and the planes of their outer edges defining an icosahedron. Corner reflector trihedrals having equilateral triangle face plane projections are referred to hereinafter as deltatrihedrals.
Although the above-described omnidirectional icosahedral radar reflector has been found useful in its functional capacity, the method of assembly is entirely restrictive. The manner of construction appears to describe a method whereby twenty individual corner reflectors (i.e., deltatrihedrals) are prepared and assembled accordingly to provide the particular configuration. Such an approach is cumbersome, time-consuming and relatively expensive and, therefore, a more expedient and economical approach in the fabrication of this particular icosahedron radar reflector as well as a family of similar multifaceted test devices would be highly desirable.
Therefore, it is an object of the present invention to provide a method of fabricating an omnidirectional orthogonal polydeltatrihedral having 90.degree. reentrant triplanar cavities; which will overcome the above-noted and other disadvantages.
It is a further object of the present invention to provide a method of constructing an omnidirectional corner reflector configuration of a compact, collapsible nature, one that is amenable to both rigid construction and inflatable construction.
A further object of the present invention is to provide an omindirectional radar reflector which can be folded into a compact assembly for ease in storage and transportation.
Yet, a further object of the present invention is to provide a method of fabricating a three-dimensional omnidirectional radar reflector from a two-dimensional network.
Yet, still another object of the present invention is to provide novel deltatrihedral corner reflectors.
Still a further object of the present invention is to provide a method of manufacturing an omnidirectional radar corner reflector having a reflector response as uniformly close to a perfect sphere as theoretically possible.